Developing Hazelnut Germplasm for the Upper Midwest

Final Report for LNC10-328

Project Type: Research and Education
Funds awarded in 2010: $175,000.00
Projected End Date: 12/31/2013
Region: North Central
State: Minnesota
Project Coordinator:
Dr. Lois Braun
Research Associate
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Project Information


Hybrids between wild native American hazelnuts (Corylus americana) and domesticated European hazelnuts (Corylus avellana) combine the disease resistance and winter hardiness of the former with the large nut size and nut quality of the latter. As a woody perennial shrub, they are a potential “Forever Green” crop for the Upper Midwest, offering multiple ecological benefits while producing a tasty and healthful human food with high market demand. The primary obstacle to their wide-scale adoption is lack of reliable improved germplasm. This project starts to address that by taking the first steps to build a breeding program.

We have now collected 157 accessions of hazelnuts (129 hybrids, 22 C. Americana, and 6 C. avellana) which are now represented in five hybrid hazelnut germplasm performance trials in the Upper Midwest (St. Paul, Lake City and Lamberton, Minnesota, and Bayfield and Tomahawk, Wisconsin). The oldest of these have been bearing nuts for three years now, so we are starting to identify the best of these to take to the next steps. 1) Some of the best have been cross pollinated with advanced selections of European hazelnuts from Oregon. About 550 seedlings of these crosses have been planted to the field and more seed from crosses are being germinated. 2) The best four selections will be micropropagated for dissemination to growers for further evaluation and to use for agronomic trials.

Dissemination of improved woody plants depends on efficient methods of vegetative propagation to develop the large numbers of clones needed. Mound layering, which was used to produce the plants in the performance trials, cannot produce the numbers needed. So we have been working to develop methods of rooting hardwood stem cuttings as an alternative. We just completed a how-to guide on the method, and have written a series of scientific papers on this research that we hope to publish in Hort Science soon. The method is not reliable enough for mass propagation, but it can produce enough plants for research purposes in situations where mound layering is not feasible. For mass propagation we will need micropropagation, which is also being developed, with different funding.

Even as we seek to improve germplasm, growers who have planted seedling stock or hope to do so soon, need advice on how to plant and manage them, so we have also been working to address their questions. Many early growers complained of poor transplant survival. So we conducted trials to determine the best kind of planting stock and the best planting time. We concluded that vigor of planting stock is imperative, and that vigor is related to a combination of pot size and age of plant. Healthy bare-root dormant stock can be planted in either fall or spring, whereas non-dormant planting stock should be planted in late summer or fall.

With this grant, we also established controlled and replicated trials to compare methods of pre-plant ground preparation, weed control, and N fertilization, using clonally-produced plants that had not been available before this grant. Earlier attempts to address these had failed because of the high level of genetic variability within the trials. Although these trials are still too young to have produced conclusive results, tentatively we recommend eliminating all perennial weeds during pre-plant ground preparation, and maintaining good weed control through the first two years of plant growth by any of a variety of methods.

For outreach we have organized an annual Upper Midwest Hazelnut Growers Conference, hosted field days and given winter seminars. For more information see our website at


The long-term goal of this project is to develop native hazelnuts (Corylus americana) and their hybrids with European hazelnuts (C. avellana) as alternative crops for the Upper Midwest, for the purpose of diversifying agriculture to enhance ecological and economic sustainability. Hazelnuts are the only woody perennial amongst the “Forever Green” crops being developed at the University of Minnesota. Ecological benefits of woody perennials include covering the soil and protecting it from soil erosion year round; reducing runoff and leaching, and thus protecting water quality both from sediments and nutrients; increasing soil carbon sequestration and enhancing soil quality; and providing habitat for wildlife. Hazelnuts can also stabilize agricultural incomes because they can provide economic return from windbreaks, shelterbelts, living snow-fences, lake and stream-bank buffers, and marginal land. They are more resilient than annual crops because they are less sensitive to drought and flooding, they have lower requirements for tillage, fertilizers, and pesticides, and timeliness of most of their management practices is not critical.

The multifunctionality of hazelnuts makes them a potential foundation species for a perennial plant-based bioeconomy. They have a four-tiered potential market: growers may sell them high-value fresh-eating nuts, as ingredients in processed foods, or for pressing into oil, and may also collect payments for the conservation services they provide. Hazelnuts are a healthful food, being high in healthful monounsaturated fatty acids, vitamin E, thiamin and fiber (Richardson, 1997). Hazelnut oil has the same healthful fatty acid profile as olive oil, and can be used in all the same ways, including in cosmetics and skin-care products. Hazelnuts also have potential as a biofuel because their oil quality is superior to soybean oil for biodiesel and because their oil content is 50 to 70% oil, about three times as high as soybeans (Xu et al., 2007). Although with current genetics hazelnut yields could not produce as much oil per acre as soybeans, individual plants evaluated in Nebraska would, if mass propagated, be able to produce three times as much as soybeans (Hammond, 2006).

The major obstacle separating this potential from reality is lack of consistent highly performing germplasm. The hybrid hazelnut seedlings available in this region descended from crosses made between Corylus americana and Corylus avellana made in the 1930s by amateur breeders to combine the disease tolerance and winter hardiness of the former with the superior nut size and quality of the latter. But in spite of breeding efforts involving multiple generations of recurrent selection, the planting stock currently available is still almost entirely seed-propagated from open-pollinated stock. This means that that the superior genetics responsible for the outstanding yields found in some individuals are not consistently passed on to their progeny. A few progeny may be like their parents or better; however, most will be inferior. It is impossible to establish hybrid hazelnut plantations that are profitable with this kind of inconsistency and unpredictability. Moreover, evaluation of parent material has not been replicated, and thus parents assumed to have outstanding characteristics may have been selected due to locally favorable environmental conditions rather than due to their genetics.

This grant is the start of efforts to establish a long-term hazelnut germplasm improvement program for the Upper Midwest. Our first steps were to identify superior hybrid hazelnut germplasm from the region’s farms, and superior wild American hazelnut germplasm from its natural areas, propagate it vegetatively with mound layering, and gather it into five replicated performance trials. This enables us to distinguish between the effects of genotype and environment, and to identify germplasm that is truly desirable. We are now moving on to the next steps—cross pollinating the best genotypes with advanced selections of European hazelnuts from Oregon, and propagating them for field scale trials, and possible eventual release as improved varieties.

Concomitant with improving germplasm, we have been working to develop more efficient methods of vegetative propagation, which will be needed to disseminate the improved varieties that we develop. The mound layering technique we used to establish our germplasm performance trials are capable of producing only a few dozen new plants per year from each mother plant. With this grant we investigated how to root hardwood stem cuttings as an alternative. This grant also enhanced our ability to secure funding to research micropropagation, which is potentially a much more productive method.

Additionally, this grant funded agronomic trials to answer some of the questions dogging the 150 some hazelnut growers we have identified in Wisconsin, Minnesota, Iowa and Illinois. We tackled the poor transplant survival of hazelnut seedlings reported by many growers with trials comparing type of transplant stock and transplant timing. We also established trials to compare methods of pre-plant ground preparation and post-plant weed control. Many hazelnut growers (who are frequently small landowners, not full time farmers) would like to plant hazelnuts into former CRP or other highly sloping land with sod ground cover, but are not equipped to till it up, nor want to because of concerns about soil erosion and soil ecology. This led us to test no-till planting of hazelnuts, even though this presents weed control challenges. Also, many growers have had the impression that weed control is not essential for hazelnuts, or else lack equipment for conventional methods of weed control, so we established trials to demonstrate both its importance and some methods that might be used. These trials will also enable us to calculate the economic return on various weed control methods.

This grant has also funded outreach events, in the form of conferences, seminars, field days and a website, to get information about improved practices out to current growers, prospective growers and the public at large. These are also important for maintaining grower enthusiasm during the long wait for improved germplasm.

Hammond, E.A. 2006. Identifying Superior Hybrid Hazelnut Plants in Southeast Nebraska. Master’s Thesis. University of Nebraska.

Richardson, D.C. 1997. The health benefits of eating hazelnut: implications for blood lipid profiles, coronary heart disease, and cancer risks. p. 295-298 In: A.I Koksal, Y.

Xu, Y.X., M.A. Hanna, and S.J. Josiah. 2007. Hybrid hazelnut oil characteristics and its potential oleochemical application. Industrial crops and products 26:69-76.

Project Objectives:

1. Plant Material
• We exceeded our target of four germplasm performance trials, with 100 accessions in each, by establishing replicated five performance trials, with 85, 92, 114, 119 and 157 accessions respectively, in triplicate to the extent possible. Of the 157 accessions represented in the largest performance trial, 22 are Corylus americana, 6 are Corylus avellana, and the remaining 129 are hybrids between the two species.
• We produced enough clonal plant material, through either mound layering or hardwood stem cutting propagation, to establish four N fertilization trials (in 2011 and 2012), four ground preparation/weed control trials (in 2013), and one plant spacing trial (in 2014). These trials are still too young to have yielded results, but results may start coming in as early as fall 2015.

2. New Knowledge
A. Commercially viable methods of hazelnut propagation
• Three papers detailing our hardwood stem cutting trial have been written and will soon be submitted to Hort. Science for peer review and publication.
• We developed a how-to bulletin on propagation of hazelnuts from hardwood stem cuttings using low-cost humidity tents. The bulletin will be posted on our website at and also on the SARE website. Although this method falls short of being commercially viable, it is useful for producing clonal plant material for research purposes in situations where mound layering is not viable.
• Our trials to improve rooting success with mound layering by figuring out how to best manage stock plant beds were inconclusive. 1) We found no differences in rooting between stock plants that were coppiced for layering after four versus three years, and 2) we found no differences in rooting between fertilized and unfertilized stock plants. We do not plan to publish this work because the experimental design was faulty.

B. Management of clonally propagated planting stock
• Type of planting stock. New information from our trials comparing different types of planting stock and different transplanting dates was incorporated into an updated version (Version 3) of our Hazelnut Production Guide, available at Briefly, we concluded that healthy bare-root dormant planting stock can be successfully transplanted in either spring or fall, though non-dormant planting stock is better transplanted in the fall. This applies to both seedlings and clonal planting material. Plants produced by mound layering can safely be left in the mound until spring if the fall transplanting window is missed. The most important determinant of transplant survival is the quality of the young plant; the best quality plants are grown with enough space for vigorous root development. Transplant survival of first year layers that were grown in a nursery bed for a year before transplanting to their final location is high, mostly because weak layers are winnowed out before transplanting, but this is offset by higher transplant cost and labor.

C. Establishment of hybrid hazelnuts
• Pre-plant ground preparation and early establishment weed control. We were overly optimistic including this trial in our 2009 proposal because we were not able to get these trials planted until we had generated sufficient quantities of clonal planting stock for them. So the weed control trials didn’t get planted until 2013, which means that it is too early for conclusive results. Subjective impressions support the advice that good weed control is important for vigorous early growth of hazelnuts, but there appear to be no differences between methods of weed control. Choices about methods will depend on the resources available to growers and their personal preferences. However, when the bushes in these trials start bearing nuts, so that we can calculate an economic return on them, some weed control methods might emerge as being more cost effective than others.

3. New Knowledge Shared with Growers and Other Researchers
Outreach activities are listed in the section on outreach.

4. The Second Upper Midwest Hazelnut Growers’ Survey was completed in Nov. 2011: A third growers’ survey in early 2014 was not completed because of poor response. Perhaps our committed growers feel like they’ve already answered our questions, leaving the growers who aren’t committed enough to respond to surveys.


Click linked name(s) to expand/collapse or show everyone's info
  • Lois Braun
  • Roy and Teresa Cerling
  • Dr. Mike Demchik
  • Norm Erickson
  • Jason Fischbach
  • Jeff Jensen
  • Dr. Brent McCown
  • Linda Meschke
  • Jim Mickelson
  • Mark Shepard
  • Dr. Don Wyse


Materials and methods:

Objective 1. Germplasm Improvement
In 2006, prior to the start this grant, we started to identify superior hybrid hazelnut (Corylus avellana x americana) germplasm growing on farms and experiment stations in Minnesota, Wisconsin, and Iowa. In 2008 we started propagating, using mound layering, the best plants identified to produce clonal material to enter into replicated germplasm performance trials for evaluation under controlled conditions. In 2010 we started a similar process with wild American hazelnuts (Corylus americana), which we started to propagate in 2013. With new germplasm being added every year, as of fall 2014 we have assembled a total of 157 accessions in our five germplasm performance trials: 129 accessions of hybrid hazelnuts, 22 of American hazelnuts, and six named varieties of European hazelnuts. These trials are located at St. Paul, Lake City and Lamberton, Minnesota, and at Bayfield and Tomahawk, Wisconsin. (Only the St. Paul trial has all 157 accessions in triplicate, because for some accessions layering failed to produce all of the 15 clones needed.)

Objective 2. Propagation Methods
A. Management of stock plant beds. We hypothesized that plants that do well in mound layering are those that have larger stores of carbohydrates and other nutrients in their roots before coppicing, which would correlate with age of plant at first coppicing, at least for plants that are still relatively juvenile. So we compared the effect of coppicing plants that were three years old at first coppice (in 2012) with plants that were four years old (in 2013), on their ability to root in mound layering. We also hypothesized that fertilization of stock plants with N would enhance rooting. For this trial, which was implemented in 2012 and 2013, we used four genotypes of plants that had been layered in 2008. The two variables (age of plant at coppicing and with and without 10g of N fertilizer per plant) were applied as a factorial, with sections of rows comprised of four to six closely spaced plants each treated as experimental units. This was because the plants were too closely spaced, at two feet apart, to treat as individual experimental units.

B. Stem cutting propagation. The methods for these trials were written up in detail in three papers that will be submitted to Hort Science for publication. In brief, we conducted experiments to determine the following for rooting hardwood stem cuttings of hybrid hazelnuts in humidity tents: 1) the optimal concentration of IBA, 2) the optimal size of stem to collect and the optimal size of segment into which to cut the stems, 3) the optimal timing to prepare stems for rooting and 4) optimal combinations of temperature and humidity. This work can also be found in a how-to bulletin that is posted at and on the SARE website.

Objective 3. Development of Best Management Practices for Establishment
A. Type of planting stock. In this trial we compared transplant survival of spring and fall dug 1st year mound layers, 2nd year mound layers and 2nd year bare-root dormant seedlings. The 1st year layers were either were dug and transplanted immediately after digging in the fall (November), or left in the mounds over winter and dug and transplanted immediately after digging the following spring (April). The 2nd year layers were dug in the fall, grown out in a nursery for one year before being transplanted to their final locations the following fall. The 2nd year seedlings were grown in an outdoor nursery through one complete growing season and dug and transplanted while still dormant the following spring. This trial was conducted on five farms and on one research station (Rosemount) with five to twelve replications per site, depending on space available. The 1st year layers were blocked by genotype.

B. Ground preparation and weed control. For this trial we planned two paired weed control trials at Rosemount and Waseca: one at each location in a previous row-crop field, with pre-plant rototilling, and the other in a sod field, in which planting strips had been prepared with only a burn down application of glyphosate, and in which planting holes were dug with an auger. Three of these trials were planted in spring 2013, using plants produced by mound layering, but the no-till site at Waseca had to be abandoned because of flooding. Instead, in fall 2013 we established a comparison of the two pre-plant ground preparation methods in paired strips in a former hayfield: in half of the strips ground was prepared with only a burn-down spray of glyphosate, and in the other half the strips were rototilled after the sod was killed with glyphosate. Rooted hardwood stem cuttings were used in the paired trial at Waseca.

Five basic weed control methods were compared in all of the trials: 1) hoeing (three to five times per season as needed), 2) landscape fabric, 3) a three inch layer of woodchip mulch, 4) a pre-emergent herbicide (Dual II Magnum, s-metoachlor), and 5) a post-emergent systemic herbicide (glyphosate) spot applied as needed two to three times per season. Control plots were merely mowed, including cross-mowing. The glyphosate was spot applied as needed in a factorial with the woodchip mulch and the pre-emergent herbicide treatments. All treatments were applied at two levels of intensity: either to 2 foot diameter circles immediately around each transplant, or to the entire 3 by 6 foot plot. Hoeing was not used in the no-till plots because it would not have been feasible in that system. The weed control treatments were implemented on single-plant plots, and replicated from five to seven times per site.

All plants were measured immediately after planting and again after dormancy in the fall. Weed pressure was estimated twice in the middle of the growing season by several methods. Percent ground cover by weeds was estimated visually within a one foot radius of the hazelnut plant and in the portion of the plot outside of that radius. The degree to which weeds within the one foot radius were crowding the hazelnut plant was also rated subjectively. The type of weed was also recorded.

Research results and discussion:

Objective 1. Germplasm Improvement
The oldest plants in the performance trials started producing nuts in 2012, and more are reaching reproductive maturity every year. By 2014 over a third of the accessions in St. Paul were bearing nuts. Nut data was collected on 85 accessions in 2014, of which a handful are emerging as being consistently superior across years and sites.

The best genotypes identified are being used, or will be used, in two ways:
1) They are being back-crossed with advanced selections of European hazelnuts from the Oregon State hazelnut breeding program to develop germplasm that is even better (specifically to improve nut quality characteristics including nut size, which are lacking in our hybrid germplasm), and
2) Some of them may be good enough for commercialization as they are. Plans are being made to propagate enough of the best four genotypes identified thus far for field-scale trials as the first step toward commercialization.

Objective 2. Propagation Methods
A. Management of stock plant beds. Contrary to expectation, we found no differences in rooting of stems in mound layering due to the age of the mother plant at coppicing, nor due to fertilization. This could have been be due to a trade-off between the larger supply of stored carbohydrates and nutrient reserves in more mature plants, and the greater juvenility of younger plants.

B. Stem cutting propagation. The results of these trials were written up in detail in three papers that will be submitted to Hort Science for publication. In brief, we concluded that 1) 2,000 ppm IBA is the best concentration for rooting hardwood stem cuttings, 2) thin stems root better than thicker ones but cuttings that are kept as long as possible root better than shorter ones, 3) dormant stems that are collected in the fall after leaf drop can be rooted after as few as three weeks of vernalization, and 4) humidity does not need to be kept at nearly 100% for rooting, though we are still not sure of the optimal humidity. Our current protocol for rooting hazelnuts from hardwood stem cuttings is posted at and on the SARE website.

Objective 3. Development of Best Management Practices for Establishment
A. Type of planting stock. We found no significant differences between rooted mound layers transplanted in November and those transplanted the following April: survival after one year was 91% and 89% for fall- and spring-transplanted respectively, a difference that is statistically insignificant. This is good news because it gives us flexibility in transplanting time, enabling us to better work around unpredictable weather. Although this survival rate was short of our target of 98% survival, we are satisfied with these results because the plants used for these trials were the weakest mound layers harvested that year. Because survival strongly correlated with quality of transplant, we are confident that if the best transplants had been used survival would have met our 98% target.

These trials also found no difference in survival between high quality 2nd year layers and high quality two-year old bare-root dormant seedlings, both of which had 100% survival. This excellent survival was probably because, with an extra year of growth, these plants were much more robust at transplanting time than the younger plants had been. Moreover, any weak plants had been naturally culled in the nursery before inclusion in the trial.

B. Ground preparation and weed control. These trials are still too young to draw many conclusions from them. Transplant mortality was not correlated with any treatment. Survival was just as good in the unweeded controls as in the weeded plots, but subjective observations suggest that unweeded plants were smaller at the end of two seasons than weeded plants. However, there were no differences in growth of the hazelnut plants attributable to pre-plant ground preparation method, weed control method or intensity of weed control.

There were major differences in the types and distribution of weeds attributable to the pre-plant ground preparation methods and to the different methods of post-plant weed control, as well as major differences in ease of implementation of the methods. In brief, as expected, annual weeds dominated in the tilled system whereas perennial weeds dominated in the no-till system. Overall, weed control was much more challenging in the no-till system. Woodchip mulch was very effective at controlling annual but not perennial weeds, but glyphosate in combination with woodchips produced nearly complete weed control. Pre-emergent herbicide was effective at controlling annual weeds in tilled plots at the beginning of the season but not later in the summer, and it was worthless against perennial weeds in no-till plots. Pre-emergent herbicide in combination with glyphosate was an effective method of weed control, but the glyphosate was difficult to apply without risk to the hazelnut plant if the weeds near the plant had already grown tall. Hoeing was very effective in controlling annual weeds, and was not as difficult as anticipated, provided that it was implemented repeatedly when weeds were small; hoeing was not used with the no-till system. Landscape fabric provided complete weed control except where it counted the most: weeds would grow up through the hole in the center of the fabric. These weeds were impossible to hoe or pull out because of their proximity to the hazelnut plant, but they could be clipped out, which was a lot of work.

Research conclusions:

Objective 1. Germplasm Improvement
In 2012 we started crossing plants in our performance trials with pollen from advanced selections of European hazelnuts from the Oregon State hazelnut breeding program. The objective of these crosses is to improve nut quality with genes from European hazelnuts. Although some degree of winter hardiness and disease resistance is likely to be lost in the first generation, we expect to recover it in the second generation. Nearly 550 back-cross seedlings resulting from these crosses have been planted in the field in St. Paul, as of fall 2014. Although we did not initially have enough data with which to make informed choices of maternal parents, selections in 2014 were based on better information, so the seed produced in 2014, which is currently being germinated, should produce some highly desirable genotypes. Pollinations conducted in 2015 will be based on even better information and should produce even better genotypes.

At the same time as we are backcrossing our best genotypes to European hazelnuts, we are taking the next steps to commercialize the best of the hybrid hazelnuts we already have. See the section on areas needing additional study for more on this effort.

Objective 2. Propagation Methods
A. Management of stock plant beds. We still do not know why some plants produce roots readily in mound layering and others do not, but age and nutritional status of the mother plant at first coppice do not explain it.

B. Stem cutting propagation. In spite of five years of trials with hardwood stem cutting propagation, we were never able to get more than 30 to 40% of cuttings to form roots. Even though we attained 90% survival of rooted hardwood cuttings, plants produced this way were not as vigorous as plants produced by mound layering. Thus we concluded that it is not likely to ever be a commercially viable method of propagation, though it does have some utility when a relatively few clones are needed and mound layering is not feasible, which is sometimes the case for research purposes. The scientific papers we wrote on the subject illustrate some basic fundamentals about stem cutting propagation for difficult-to-root species, and will contribute to discussions about how the method might still be improved. The how-to bulletin may be useful for hobbyists or for small scale nursery producers.

Objective 3. Development of Best Management Practices for Establishment
A. Type of planting stock. Lessons learned from this trial were incorporated into our 3rd Version of our guide “Growing Hybrid Hazelnuts”. In brief, this trial demonstrated that there is flexibility in transplanting time, which enables growers to better work around unpredictable weather and soil conditions. We recommend transplanting in the fall if possible, since soil conditions tend to be better in the fall, and since spring transplanting can then be a back-up if something goes wrong.

Results also demonstrate that survival is improved by growing planting stock out in a nursery for a year before transplanting it to its final location, though this is mostly attributable to the fact that plants that would not have survived are culled before that stage. Whether or not this is worth the additional expense depends on the relative costs of managing it in a nursery versus managing it in the field.

Likewise, seedlings that are transplanted bare-root dormant after a full year in a seedling bed have much higher survival than younger seedlings. In the case of seedlings grown in outdoor beds, the additional cost of keeping them this long is minimal, so they are definitely worth the expense. This is in contrast to containerized seedlings, which need to be continuously up-potted to larger pots to prevent stunting their growth and permanently retarding them, for which 2nd year seedlings are significantly more expensive. In an earlier trial (before the start of this grant) we tested pot size and concluded that seedlings are best grown tubes no smaller than 10 by 3 inch tubes or 1 gallon pots. See Although we have not tested this in replicated trials, our experience and that of other researchers suggests that hazelnuts should not be transplanted leaf-on (non-dormant) before late summer or fall.

B. Ground preparation and weed control. The final analysis of this trial will be to determine whether the differences observed in weed type and distribution have an impact on hazelnut growth. When the plants in these trials start to bear nuts we will be able to calculate an economic return to management for the different methods of weed control. Differences between the methods in cost, labor and worry will also factor into this analysis.

Economic Analysis

An economic analysis was not a deliverable on this grant. However, Jason Fischbach with the University of Wisconsin developed an Enterprise Budget Tool for hybrid hazelnuts which is available at

Farmer Adoption

The most important product of this project will be improved germplasm, but because hazelnuts are slow-growing perennials, improved varieties are not yet available. Thus growers have not had the opportunity to adopt them yet. One of the impacts of our outreach efforts has been to impress upon growers, both current growers and prospective growers, the challenges of working with our current genetics, which has dissuaded many from planting them. We have heard from some current growers that they plan to replace their existing plantings with improved varieties when they become available.

We do not know to what extent new growers have been relying on our Hazelnut Production Guide for recommendations on how to establish new plantings.

Other publications (such as the bulletin on how to propagate hazelnuts from stem cuttings) have only recently been released, so there has not been time for growers to adopt them yet. The stem cutting protocol is not especially grower friendly, as it calls for a greenhouse with good temperature controls, but it might be useful for current or prospective nursery growers, though ultimately we expect micro-propagation to be a more productive method.

Participation Summary

Educational & Outreach Activities

Participation Summary:

Education/outreach description:

• Our website, receives about 200 unique hits per week. New material developed with information developed with this grant and posted on the website include:

o “Growing Hybrid Hazelnuts, Version 3”, a production guide by Lois Braun and Jeff Jensen was updated with information about type of planting stock and planting date that was developed with this grant

o “How to Propagate Hybrid Hazelnuts from Hardwood Stem Cuttings”, by Lois Braun came out of research funded by this grant.

• Three papers detailing our hardwood stem cutting research have been prepared for submission to Hort. Science.
• We held an Upper Midwest Hazelnut Conference every year of the grant:

o March 4-5, 2011, South St. Paul MN, attended by 48 people

o March 2-3, 2012, Decorah IA, attended by 57 people

o March 1-2, 2013, Eau Clair, WI, about 50 people

o March 7-8, 2014, Gays Mills, WI, about 40 people

• We hosted or presented at least two field days or seminars per year:

o Oct 2010, presented a research update at Hazelnut Valley Farm, Lake City, MN, attended by 35 people

o July 2011, Hazel Acres, Fenton, IA, attended by 22 people

o Aug 2011, Rosemount ROC annual open house with about 2,200 visitors; we hosted a table visited by about 100 people

o Oct 2011, presented a research update at Hazelnut Valley Farm, Lake City, MN, attended by 41 people

o May 20, 2012, Hazelnut Valley Farm tours with Slow Foods Minnesota, about 100 people

o July 26, 2012, Rosemount ROC hazelnut research plots, attended by 5 people

o Oct 6, 2012, presented on pruning and coppicing trials at Hazelnut Valley Farm, Lake City, MN, attended by 50 people

o March 11, 2013, Rural Advantage Third Crop Producer Meeting, Fairmont Minnesota, about 15 people

o Aug 20, 2013, Rural Advantage Walk N Talk, St. Paul hazelnut research plots, about 10 people

o Jan 16, 2015, presented “Hazelnuts as a potential new crop for MN” at the Minnesota Fruit and Vegetable Growers Association conference, St. Cloud, MN.

• Our work was presented at two regional or national conferences:

o Nov 21-22, 2013, a poster at Green Lands Blue Waters conference, Minneapolis.

o Aug 10-13, 2014, an overview of the Upper Midwest Hazelnut Development Initiative was presented at the Northern Nut Growers Association conference, Corvallis, OR.

Project Outcomes


Areas needing additional study

Objective 1. Germplasm Improvement
When hybrid hazelnuts, which have a high level of winter hardiness and resistance to Eastern Filbert Blight (EFB) are crossed with advanced selections of European hazelnuts from Oregon, we can expect their offspring (the BC1 generation) to have improved nut quality but also to have reduced hardiness and EFB resistance. We believe that these essential traits will be recovered in the second generation (the BC1F1 generation), but do not know for sure, because we do not know much about the inheritance of either winter hardiness or Corylus americana-derived EFB resistance. Identifying patterns of inheritance of these traits may enable us to make better selections of parent material for future crosses, crosses that would result in a higher portion of offspring that combine all desired traits. We hope to secure funding for a graduate student to do this work.

We are taking the first steps to commercialize the best of the hybrid hazelnuts identified so far. In fall 2014, we collected suckers from the eight best genotypes identified thus far to establish in culture for micropropagation. 400 clones of the best four of these (based on 2014 yield data and on performance in culture) will be produced for establishment in four field-scale trials. One-quarter acre will be planted of each of the four genotypes in each of the four trials. Because of their relatively large scale and uniformity, these plantings will enable us to: 1) experiment with mechanized systems for managing hybrid hazelnuts, especially for harvest, 2) develop more efficient processing systems with the larger volumes of nuts expected, which will also help with market development, and 3) conduct better replicated agronomic trials to answer questions about fertilization, irrigation and pruning, etc., questions that have eluded answers because trials thus far have been confounded by too much genetic variability within reps.

Objective 2. Propagation Methods
A. Management of stock plant beds. Many papers suggest that manipulating stock plant beds with various methods that keep suckers small and juvenile improve rooting from cuttings, and the same is likely true with mound layering. This includes reducing the fertility of the stock plants. Thus it might be worth repeating this experiment, but with mother plants spaced far enough apart that they do not interfere with each other. This would require digging the stock plants up and replanting them at wider spacing. This experiment is not a high priority.
B. Stem cutting propagation. Further trials are needed to determine optimal temperature and humidity ranges for rooting hardwood stem cuttings, and to develop simple low-cost methods for maintaining humidity tents at the optimal levels. Further trials might also examine whether shaving off the cuticles of cuttings, especially thick cuttings, might enhance rooting, and whether the IBA concentration might need to be adjusted for stems that have been shaved.

Objective 3. Development of Best Management Practices for Establishment
A. Type of planting stock. We are satisfied with our conclusions of this study, together with a study on pot size completed prior to this grant, available at
B. Ground preparation and weed control. For this study we should have considered mowing to be another weed control treatment, leaving the control plots completely un-mowed, as we believe that simple mowing may confer some benefit by reducing competition for moisture.

Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.